react / react/react-native

Fontsize changing only once with systems settings in Android 15

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#49,459 5 comments 2 reactions 0 assignees View on GitHub

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Issue: Author Provided Repro Platform: Android
Dominant language
C++
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Forks
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Avg merge
1d 23h
Merged PRs (30d)
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Description

Description

When changing the sytems fontsize a react native application in Android does not change the fontsize until it is restarted, in Android versions <=14 it is rerendered in the new fontsize on the fly.

Steps to reproduce
  1. create new project from via npx @react-native-community/cli@latest init projectname and begin running it
  2. Use two android version for this test , particularly use Android 14 Pixel 8 , and another Android 15 Pixel 8
  3. start example app
  4. change fontsize at least two times -> Android 14 font resizes, Android 15 font stays the same

Android15 stays the same after changing fontSize:
Image
Android15 after restart with changed fontSize:
Image

Android14 before changing size:
Image
Android14 afterchanging size:
Image

Video showing only first fontSize change has effect until restarting App:

https://github.com/user-attachments/assets/42a4a157-6c72-4a99-aa9e-c315b9071adb

React Native Version

0.77.1 and before

Affected Platforms

Runtime - Android

Output of npx @react-native-community/cli info
System:
  OS: macOS 15.3.1
  CPU: (12) arm64 Apple M3 Pro
  Memory: 1.34 GB / 36.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 21.6.2
    path: ~/.nvm/versions/node/v21.6.2/bin/node
  Yarn:
    version: 1.22.21
    path: ~/.nvm/versions/node/v21.6.2/bin/yarn
  npm:
    version: 10.2.4
    path: ~/.nvm/versions/node/v21.6.2/bin/npm
  Watchman:
    version: 2024.12.02.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.2
      - iOS 18.2
      - macOS 15.2
      - tvOS 18.2
      - visionOS 2.2
      - watchOS 11.2
  Android SDK:
    API Levels:
      - "33"
      - "34"
      - "35"
    Build Tools:
      - 30.0.3
      - 33.0.0
      - 33.0.1
      - 34.0.0
      - 35.0.0
    System Images:
      - android-34 | Google APIs ARM 64 v8a
      - android-35 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2024.2 AI-242.23726.103.2422.12816248
  Xcode:
    version: 16.2/16C5032a
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.10
    path: /Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home/bin/javac
  Ruby:
    version: 2.7.8
    path: /opt/homebrew/opt/ruby@2.7/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 15.0.1
    wanted: 15.0.1
  react:
    installed: 18.3.1
    wanted: 18.3.1
  react-native:
    installed: 0.77.1
    wanted: 0.77.1
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: Not found
  newArchEnabled: false
Stacktrace or Logs
nothing
Reproducer

https://github.com/recumbentseeker/fontscale

Screenshots and Videos

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the linked fontscale reproducer on Android 14 and Android 15, then repeat the system font-size changes described in the issue. Compare the behavior before and after an app restart and trace the Android runtime handling involved. Done means font-size changes continue to update the React Native app without requiring a restart, while Android 14 behavior remains intact.

Written by the indexing model from the issue text.

Assessment

Tech stack
android
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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